Cannula configured to deliver test stimulation

Abstract

An implant tool and cannula facilitate the implantation of a medical device into a patient. The implant tool includes a housing that is held by a user and a needle attached to the housing. The cannula may be positioned over the needle and delivered to a target tissue within the patient. The cannula includes an electrode at a distal portion to deliver test stimulation to confirm the location of the target site or placement of the implant tool relative to the target site before removing the needle of the implant tool. In this manner, the cannula may be repositioned within the patient until the position of the implant tool and cannula relative to the target site is verified with the test stimulation.

The invention claimed is: 
     
       1. A cannula comprising:
 an elongated housing defining a lumen configured to allow passage of a medical device; 
 at least one of a partial ring electrode or a segmented electrode positioned on a distal portion of the elongated housing, wherein the distal portion of the elongated housing defines a portion of the lumen, and wherein the at least one of the partial ring electrode or the segmented electrode extends around less than an entire outer circumference of the elongated housing; 
 an electrical contact positioned on a proximal portion of the elongated housing; and 
 a conductive element that resides within the elongated housing and electrically couples the at least one of the partial ring electrode or the segmented electrode to the electrical contact. 
 
     
     
       2. The cannula of  claim 1 , wherein the elongated housing comprises a shape memory material. 
     
     
       3. The cannula of  claim 1 , wherein the lumen defined by the elongated housing is configured to receive a needle of an implant tool. 
     
     
       4. The cannula of  claim 3 , wherein a portion of the needle extends past the at least one of the partial ring electrode or the segmented electrode when the needle is positioned within the lumen of the cannula. 
     
     
       5. The cannula of  claim 1 , wherein the at least one of the partial ring electrode or the segmented electrode comprises a plurality of electrodes located at different circumferential positions around the distal end of the elongated housing. 
     
     
       6. The cannula of  claim 5 , further comprising a plurality of electrical contacts located at the proximal end of the elongated housing, wherein each of the plurality of electrical contacts are electrically coupled to one of the plurality of electrodes via separate conductive elements. 
     
     
       7. The cannula of  claim 1 , wherein the conductive element substantially defines a helical or spiral arrangement within the elongated housing between the proximal end and the distal end. 
     
     
       8. A system comprising:
 a cannula comprising:
 an elongated housing defining a lumen configured to allow passage of a medical device; 
 at least one of a partial ring electrode or a segmented electrode positioned on a distal portion of the elongated housing, wherein the distal portion of the elongated housing defines a portion of the lumen, and wherein the at least one of the partial ring electrode or the segmented electrode extends around less than an entire outer circumference of the elongated housing; 
 a first electrical contact positioned on a proximal portion of the elongated housing; and 
 a conductive element that resides within the elongated housing and electrically couples the at least one of the partial ring electrode or the segmented electrode to the first electrical contact; and 
 
 an implant tool comprising:
 an implant tool housing; 
 a needle coupled to the implant tool housing and configured to be inserted into tissue of a patient and to fit within the lumen of the cannula; and 
 a second electrical contact configured to electrically couple to the first electrical contact. 
 
 
     
     
       9. The system of  claim 8 , wherein the elongated housing comprises a shape memory material. 
     
     
       10. The system of  claim 8 , further comprising:
 a plurality of electrodes located at different circumferential positions around the distal end of the elongated housing, the plurality of electrodes comprising the at least one of the partial ring or the segmented electrode; and 
 a plurality of electrical contacts located at the proximal portion of the elongated housing, wherein each of the plurality of electrical contacts is electrically coupled to one of the plurality of electrodes via separate conductive elements, the plurality of electrical contacts comprising the first electrical contact. 
 
     
     
       11. The system of  claim 8 , further comprising a signal generator that generates test stimulation delivered to the tissue via the electrode of the elongated housing. 
     
     
       12. The system of  claim 8 , wherein the implant tool comprises:
 a flange that extends near a side of the needle and defines a channel configured to accept the cannula between the needle and the flange; and 
 a release mechanism configured to move the cannula toward a distal end of the needle. 
 
     
     
       13. The system of  claim 8 , further comprising an electrical stimulator configured to couple to the second electrical contact of the implant tool. 
     
     
       14. The system of  claim 13 , wherein the electrical stimulator is located within the implant tool housing. 
     
     
       15. The system of  claim 8 , wherein a portion of the needle extends past the at least one of the partial ring electrode or the segmented electrode when the needle is positioned within the lumen of the cannula.